An example of various types of eco-friendly vehicles which are now being developed and are attracting attention may be an electric vehicle.
The electric vehicle is driven by charging and discharging energy of a battery pack. Therefore, the electric vehicle may have more excellent fuel efficiency and more reduce pollutants than a vehicle using only an engine and therefore has received a positive consumer response. Therefore, a battery which is a core component of the electric vehicle has been more intensively researched.
As products using the battery are increased, a need exists to keep a voltage of the battery high. For this reason, the voltage of the battery is greatly reduced at a low state of charge (SOC) and a low temperature, which has a bad effect on system efficiency. In particular, the system efficiency is more affected at the low temperature at which the power output is reduced.
Generally, polyethylene(PE)-based parts set a minimum voltage from the battery as a reference voltage. In this case, it is preferable to keep the reference voltage of the PE-based parts higher.
For this reason, to prevent the voltage drop of the battery cell, a method for setting the reference voltage of the PE-based parts to the minimum voltage of the battery and increasing the reference voltage is used.
In this case, as illustrated in FIG. 1, the SOC and temperature of the battery are measured and a maximum output quantity of the battery is determined depending on the measured SOC and temperature of the battery (steps S110 and S120).
The voltage drop of the battery occurs depending on the maximum output quantity of the battery and the maximum output quantity of the battery is also reduced (steps S130 and S140).
Therefore, the method for increasing the reference voltage considerably disturbs the improvement in system efficiency and the reduction in weight and therefore a need exists for a method for increasing a minimum voltage.